The present invention relates to an improved control handle for a bi-directional steerable catheter.
Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity.
In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral artery, and then guided into the chamber of the heart which is of concern. Within the heart, the ability to control the exact position and orientation of the catheter tip is critical-and largely determines how useful the catheter is.
Steerable catheters are generally well-known. For example, U.S. Pat. No. RE 34,502 describes a catheter having a control handle comprising a housing having a piston chamber at its distal end. A piston is mounted in the piston chamber and is afforded lengthwise movement. The proximal end of the catheter body is attached to the piston. A puller wire is attached to the housing and extends through the piston and through the catheter body. The distal end of the puller wire is anchored in the tip section of the catheter. In this arrangement, lengthwise movement of the piston relative to the housing results in deflection of the catheter tip section.
The design described in U.S. Pat. No. RE 34,502 is generally limited to a catheter having a single puller wire. If a bidirectional catheter is desired, i.e., a catheter that can be deflected in more than one direction without rotating the catheter body, more than one puller wire becomes necessary. When two puller wires are used, however, it is undesirable for both wires to be moved simultaneously. The handle design disclosed in U.S. Pat. No. RE 34,502 is not suitable for a two puller wire system. Accordingly, a need exists for a control handle capable of independently moving each of two puller wires but preventing simultaneous movement of the puller wires.
The invention is directed to an improved bidirectional steerable catheter. In one embodiment, the catheter comprises an elongated, tubular catheter body having at least one lumen extending therethrough. A tip section comprising flexible tubing having at least two lumens extending therethrough is fixedly attached to the distal end of the catheter body.
A control handle is mounted to the proximal end of the catheter body. The control handle comprises a generally-hollow handle housing having inside and outside surfaces and a generally tubular core extending longitudinally within the housing. A generally-circular spur gear is rotatably mounted within the handle housing, the spur gear having teeth about its outer circumference. First and second pistons are slidably mounted on diametrically opposed sides of the spur gear and at least partially in surrounding relation to the tubular core within the handle housing. Each piston has an interior edge generally facing the interior edge of the other piston and comprises a series of teeth along its interior edge that engage the teeth of the spur gear so that proximal movement of one piston results in rotational movement of the spur gear and distal movement of the other piston. A longitudinally movable thumb control is fixedly attached to the first piston and accessible from outside the handle housing.
The catheter further comprises first and second puller wires having proximal and distal ends. Each puller wire extends from the control handle, through a lumen in the catheter body and into a lumen in the tip section. The distal end of each puller wire is fixedly attached to the tip section. The proximal end of the first puller wire is anchored to the first piston, and the proximal end of the second puller wire is anchored to the second piston.
Proximal movement of the thumb control relative to the handle housing results in proximal movement of the first piston and first puller wire relative to the handle housing and catheter body, which results in deflection of the tip section in the direction of the lumen into which the first puller wire extends. Distal movement of the thumb control relative to the handle housing results in distal movement of the first piston, causing proximal movement of the second piston and puller wire relative to the handle housing and catheter body, which results in deflection of the tip section in the direction of the lumen into which the second puller wire extends.
In another embodiment, the invention is directed to a catheter comprising a catheter body having a tubular wall, proximal and distal ends, and at least one lumen extending therethrough. A control handle is mounted to the proximal end of the catheter body. The control handle comprises a housing having proximal and distal ends and an interior core within the housing and attached to the catheter body. A fastener mechanically connects the handle housing to the core through an opening in the handle housing. The fastener comprises a body having a top side and a bottom side that fits within the opening in the handle housing and at least two flexible prongs extending from the underside of the body that mate with the core.
In another embodiment, the invention is directed to a catheter comprising a catheter body having a tubular wall, proximal and distal ends, and at least one lumen extending therethrough. A control handle is mounted to the proximal end of the catheter body. The control handle comprises a housing having proximal and distal ends, a tubular core within the housing and fixedly attached to the housing and catheter body, and a n interior member within the housing having proximal and distal ends and being longitudinally moveable relative to the housing and tubular core. A washer comprising a proximal ring and an outer wall extending distally therefrom is mounted about the tubular core. A flexible o-ring having inner and outer surfaces sits within the washer so that the outer surface of the o-ring is in contact with the outer wall of the washer and the inner surface of the o-ring is in contact with the core. A thumb control knob is threadably-engaged to the distal end of the interior member. When the thumb control knob is screwed onto the proximal piston, it compresses the o-ring into the washer, pressing the inner surface of the o-ring against the core so that the user can adjust the tension on the thumb control by screwing or unscrewing the thumb control.